In season 7, 13 yo Elizabeth wearing shorter but thick pigtails and medium blue bib overalls. Pic at 2h22 on disc 3 ep 11 (12 in Germany). Also shown completetly front+rear.
Another good scene at 2h57.
More infos and pic, also of earlier episodes on my bib overalls blog.
Main entry and some separate posts here, rating 10 (including younger Elizabeth and others like Erin and Mary Ellen) at